Apparatus for the production of tubular metallic objects



July 3, 1956 P. ROBERT 2,753,545

APPARATUS FOR THE PRODUCTION OF TUBULAR METALLIC OBJECTS Filed March 51,1952 4 Sheets-Sheet 1 I72 venfok Piu'zi o oe Raber-Z July 3, 3856 P.ROBERT 2,752,648

APPARATUS FOR THE PRODUCTION OF TUBULAR METALLIC OBJECTS Filed March 31,1952 4 Sheets-Sheet 2 I A \K ITZV7ZZ Ofi Pill a ue Ro er-Z W1 gfgpy; W

P. ROBERT July 3, 1956 APPARATUS FOR THE PRODUCTION OF TUBULAR METALLICOBJECTS 4 Sheets-Sheet 3 Filed March 51, 1952 xZ a 0 I72 venoh PA 529006: 1% LerZ l //1///// r M /u/ 0 July 3, 1956 P. ROBERT 2,752,648

APPARATUS FOR THE PRODUCTION OF TUBULAR METALLIC OBJECTS Filed March 31,1952 4 Sheets-Sheet 4 iiz APPARATUS FOR THE PRODUCTION OF TUBULARMETALLIC OBJECTS Philippe Robert, Paris, France, assignor to SocieteCivile dEtudes de Centrifugatiou, Paris, France, a corporation of FranceApplication March 31, 1952, Serial No. 279,656 Claims priority,application France April 5, 1951 3 Claims. (Cl. 22-572) This inventionrelates to the production of hollow or tubular metallic objects by acontinuous process, and more particularly to means for directlyproducing such objects from molten metal. The resulting hollow metallicobjects obtained according to the invention may serve both directly asfinished tubular articles or they may serve as blanks to be eventuallysubjected to additional machining or other finishing operations.

The production of steel tubing by conventional methods involves acomplex sequence of steps requiring the use of extensive and expensiveequipment. Such conventional steps may by way of example be summarizedas follows:

a. The metal is first melted and refined in a furnace or a converter;

b. The molten metal is then 0. The ingots are rolled in a blooming mill;

(1. Top and bottom ends are lopped off for removing bloom portionsshowing pipes, segregation, cracks, blowholes and similar defects allresulting from the discontinuous manner in which the ingots were cast;

6. In some cases the blooms are re-heated;

f. The blooms are next rolled into round bars and cut to length;

g. The lengths of round bars are heated;

h. The heated bars are rolled in a drilling mill; and

i. The resulting tubular blanks are passed in a finishing mill.

The resulting over-all cost of the tube is very high, especially owingto the following factors involved in the above described operations:

1. High depreciation and maintenance costs of the plants;

2. Considerable man-power, energy and fuel requirements;

3. Considerable loss of material incurred in the respective stages ofmanufacture: For example, as stated, the end portions of the ingots mustbe lopped off; also the ends of the round bars must be sawed off;further losses are incurred by oxidation during the successive reheatintreatments. The overall weight ratio from the molten metal required tothe completed blank may be put at about 1500/1000.

It is an object of this invention to overcome the above objectionablefeatures of conventional tube making processes and more particularly toproduce blanks directly from the molten metal, thereby eliminating allthe abovenoted steps (b) through (i).

Another object is to produce directly and without delay finishedmetallic objects of tubular or hollow form.

According to the invention, molten metal is directly poured into one endof a revolving mold open at both ends in which the metal is allowed tosolidify; the solidified metal casting is continuously withdrawn fromthe mould through the other end thereof, the rate of withdrawal beingregulated in correlation with the rate at which the molten metal is fedinto the revolving mold.

With the arrangement described, the metal fed into cast in ingot molds;

, 2,752,648 Patented July 3, 1956 the mold in liquid state isimmediately and forcibly applied against the inner walls of the mold bycentrifugal force and is thus caused to assume, as it solidifies, ashape conforming to that of the internal wall of the mold whileretaining an axial recess. Force is exerted at the outlet of the mold onthe solidified portion thereby to extract the resulting hollow blank ina continuous way, thus at the same time clearing at the top of the molda free space which will receive the fresh molten metal into sections ofany desired length without requiring discontinuation of the process. Animportant advantage is the possibility of thus producing tube sectionshaving any desired length whatever. Anotherimportant advantage is thatsubstantially no loss of metal is incurred throughout the process.

In addition to the economical advantages of the method of thisinvention, there that products of improved characteristics are obtainedas suiting blanks are uniform in thickness and are highly homogeneous instructure and composition.

The invention is applicable to all metals, both ferrous and non-ferrous.In this respect, its use is especially advantageous in connection withmetals unsuitable for rolling, such as very high-carbon steel, grades ofalloy steel having a high nickel content, a high chromium con tent, andthe like, cast iron, unforgeable grades of bronze or brass, etc. Thusthe invention provides a new technique for producing tubular objectsfrom all such materials from which it was hitherto difiicult orunpractical to produce such objects by the conventional processes owingto the poor working characteristics of the materials.

According to an important further object and feature of the invention,in contradistinction with the known methods of tube manufactureinvolving a series of successive, discrete steps or operations, thepresent process comprises but a single integral operation comprising aseries of simultaneous phases correlated with one another in aharmonious manner, viz: feeding molten metal to the rotating mold,centrifugal action within the mold, molding, solidification anddischarge out of the mold.

The mold is preferably provided with an auxiliary adjustable coolingmeans for adequately cooling the tubular blank being formed bycentrifuging. This cooling reresults in a contraction which separatesthe solidified tube from the inner mold wall and facilitates withdrawalthereof in a continuous and smooth manner.

Owing to the continuous solidification and extraction, the phase offeeding metal to the mold may be performed in a smooth and continuousway, and the semi-solid or solid metal serves as a support for theliquid metal delivered into the mold and forced against the wall thereofduring the rotation imparted to it.

It has heretofore been suggested to produce tubes by so-calledcontinuous casting processes where by a tubular blank or finished tubemay be produced from molten metal in an appropriately constructedsuitably cooled mold. In these old methods however no rotary mold wasprovided, and the use of an internal core or mandrel was thereforeindispensable. It is an object and a feature of the present invention toprovide a revolving mold which owing to the centrifugal efiect developedwill promote easy, positive and reliable formation of a hollow tubularbody.

I am also aware that the use of centrifuging has been proposed for theproduction of hollow or tubular articles from liquid metal. However,conventional methods of this character and the devices used in carryingthem into tubes of very restricted length, by a discontinuous andintcrmittent process, resulting in a considerable proportion of, scrap,shut-downs and idle periods, leading to a low over-all efiicicncy ratioand high cost.

Furthermore, an object and a feature of the invention reside in the use,in conjunction with conventional centrifuging pipe making processes ofthe discontinuous or batch type, a continuous discharge of the formedpipe correlated with a continuous feed of the molten metal. Whereasheretofore a centrifuging process was applied in discrete alternatingsteps, according to the invention centrifuging is applied in combinationwith a continuous pouring phase and a simultaneous continuous dischargeor extraction phase, whereby a tubular casting of unlimited length isproduced which can be cut to desired lengths independently of itsproduction in a subsequent step or phase of operation, as dictated byrequirements of shipping or of service.

The invention will now be described in greater detail with reference tosome specific embodiments of apparatus usable in carrying it intopractice, it being understood that said embodiments are given by way ofillustrative examples and are in no way restrictive of the iuventionsscope. In the accompanying drawings:

Fig. 1 is a general diagrammatic view of one form of embodiment;

Fig. 2 ShOWs in greater detail the construction of a modified form ofrotary mold used in the embodiment of Fig. l, as seen in section;

Fig. 3 depicts the continuous metal into the mold;

Fig; 4 shows an alternative system in which the said continuous feedingphase may be embodied;

Fig. 5 relates to the discharge phase for continuously extracting thetubular casting from the mold; and

Fig. 6 illustrates one form of cutting means.

As shown in Fig. l, the invention comprises in combination, means 11 forcontinuously feeding molten metal, a rotary mold 12 and a continuousextracting or discharge device 13 for extracting the solidified blankformed in the mold 12.

The continuous feed means 11 comprises a pocket 14 supplied with moltenmetal from any suitable melting apparatus or furnace not shown. Thepocket 14 may have re-heating means associated with it, such as heatingresistors, high frequency induction heating coils or the like;

Such means are well-known in the art and have not been illustrated.Formed in the bottom of the pocket 14 is an outlet 15 delivering intothe top inlet of a funnel, chute or runner 16 terminating in a jetoutlet 17 adapted to discharge the liquid metal at a point adjacent tothe inner wall of the rotary mold 12 in the form of a generally circularjet or sheet. A suitable control member 18 is provided for regulatingthe discharge of liquid metal delivered into the mold.

The rotary mold 12 essentially comprises a shell 19 generally ofcylindrical form. Integrally connected with the shell is a gear annulus20 meshing with a drive pinion 21 driven from any suitable drive means,not shown. Surrounding the cylindrical surface of the mold shell 19 area plurality of jet pipes 22 from which a coolant fluid may be dischargedon the periphery of the shell.

The continuous extraction assembly 13 may assume any of various forms.As shown by way of example in Fig. 1, it comprises a set of rollers 23rotated on inclined axes. The angle of inclination of the roller axes isadjustable as is also the spacing between the peripheries of therollers. The angular rate at which the rollers are simultaneouslyrotated is also adjustable so that, for any given diameter of pipingbeing made, the linear tangential speed of each of the rollers 26 can bemade equal to the tangential speed of the inner wall of the rotary mold19.

feeding phase of molten It will be seen that with the above describedarrangement, molten metal discharged from the feeder 11 into the mold 12which is revolving at a constant speed, is forcibly applied against theinner wall of shell 19 and quickly solidifies thereon under the coolingeffect of the surrounding air and/or the coolant fluid delivered from22. A tubular blank or casting A is thus continuously formed. This blankA is continuously fed out of the mold progressively as it forms andsolidifies on the walls of the mold, under the action of the rollers 23.The blank as it is fed out of the mold continuously clears a free spaceat the top of the shell 19 adapted to receive a fresh supply of moltenmetal from the jet 17. Although description of the process necessitatesthe recitation of discrete steps, the cycle will of course be understoodto be continuous, involving the simultaneous correlated phases offeeding centrifuging, molding, solidification, and discharge. Acontinuous tubular casting is thus produced.

This continuously cast blank A is of course cut to desired lengths byany suitable means, as by sawing, blow-pipe or the like.

By acting on the angle of the axes of rollers 23 with respect to theaxis of rotation of the mold, the rate at which the blank A is extractedfrom the mold 12 may be controlled in correlation with the rate at whichmolten metal is fed into the top of shell 19. The adjustment of 7 thisrate of feed is further completed by means of the control member 18cooperating with outlet 15. The resulting tubular blank A is then cutinto lengths of suitable size suitable for treatment by the usualrolling, drawing and other working steps for converting the blanks intopipes of the requisite dimensions.

In one form of embodiment (Fig. 2), the rotary mold comprises a shell 24supported by an upper taper bearing surface 25 in centered relationshipto a rotary member 26 and by a lower cylindrical bearing surface 27 withrespect to a second rotary member 28. This arrangement makes it possiblerapidly to remove the shell 24 by pulling it upwards for replacement orother purposes, without having to dismantle its drive mechanism or otheraccessory parts.

The shell 24 is connected for rotation with the rotary members 26 and 28through suitable cooperating stops or projections. The members 26 and 28are driven in rotation through gear annuli 29, 30 meshing respectivelywith pinions 31, 32 secured on a shaft 33. Shaft 33 is driven throughpulley 34 from a suitable source of motive power. The rotary members 26,28 are supported from a frame comprising the frame elements 35-36 andtop element 37, through suitable ball, roller or needle bearings 38. Acover plate 39 is provided for sealing the central aperture in top frameelement 37.

Within the rotary member 26 separate circular conduits 40, 41, 42, 43are provided, supplied with a suitable cooling fluid such as water whichis delivered on to the outer surface of shell 24 through suitablenozzles directed inwardly from the circular conduits. The circularcooling pipes are preferably each provided with its control valve, notshown. The cooling liquid impinging on the outer wall, of mold shell 24,streams down the wall and flows down the drip-surface 44, collecting inan annular trough 45 whence it is discharged through drain pipe 46. Theshell 24 is provided with an inclined drip-flange 47, and the surface 44has an overlying drip-plate 48 thereon to allow discharge of the coolingfluid while preventing its ingress into the underlying portions of themechanism. An additional circular cooling pipe 49 with discharge nozzlesor apertures therein may be provided at the top of the shell above thecover plate 39. The mold assembly thus provided is secured to thegeneral frame of the machine or to suitable supporting structure bymeans of a base flange 50.

It will be noted'that according to the arrangement described the moldshell 24 is so mounted as to allow free expansion thereof relative toits supports. To this end the necessary clearance is allowed for whererequired. As stated, the shell can readily be removed and replaced. Forthis purpose, it is only necessary to remove the protecting plate 39 andpull the shell upwards.

Fig. 3 shows on an enlarged scale one embodiment of the means forcontinuously feeding molten metal into the rotary mold. The pocket 14receives the liquid metal and supplies the mold through outlet 15,runner 16 and removable nozzle 17. Outlet 15 is provided with a sealingplug 18, supported from a shank 52, this plug assembly being adjustablein the up-and-down direction. The plug assembly serves to complete thefine adjustment of the rate of feed for accurate correlation thereofwith the rate of discharge of the centrifuged and solidified blank A Thepocket 14 is internally lined with refractory material or any othersuitable lining composition 53 in which heating resistor or inductioncoil element 54 are shown as imbedded.

In the construction illustrated, the mold shell 24 is provided at itslower end with a circular metal casing 55 provided with a refractorylining 56 so as to define a circular chamber 57 into which the moltenmetal discharged from nozzle 17 is delivered. Owing to this arrangement,the molten metal as it impinges on the surface of shell 24 is retained,and forcibly applied by centrifugal force into the annular chamber orgroove 57 which it first fills up and whence it then overflows in theform of an annular sheet into the mold proper 24. and uniform supply ofmetal into the mold is obtained.

Inert or reducing gas may be admitted into or produced locally byincomplete combustion of hydrocarbons in the mold chamber adjacent tothe groove 57 and the entire upper part of the inner space of the assurethat the feed of molten metal and the formation of the inner wall of thetubular blank being produced, will occur in a suitable nonoxidisingatmosphere.

A smooth continuous feed is insured by maintaining a constant level ofthe molten metal in the pocket 14, and for this purpose the pocket 14may be supplied from a further pocket or ladle filled from the meltingfurnace, the metal being poured from the ladle either directly or bymeans of a stopper-rod into the pocket 14, and the outflow section ofthe removable nozzle 17 being suitably predetermined.

In the modified form shown in Fig. 4, the pocket or crucible 14 is fixedand is formed in its bottom with an outflow orifice 58. Secured withinthe rotary mold in the upper part thereof is a bushing member 59 sealedby an end wall 60 at its lower end and internally lined with refractorycomposition. Formed through the sides of the metal first collects uponadmission thereof into the mold 5556.

The outer diameter of bushing member 59 is substantially equal to theinner diameter of the tubular blank A to be produced; in other words,between the bushing member 59 and the inner wall of mold 55 a space isdefined which corresponds to the skin thickness of the blank A.

In this form of embodiment, the annular chamber 57 provided withstraight walls, is preferably formed with a curved configuration incross sec- Thus, its upper wall section is shown as substantially beingin the form of a paraboloid of revolution 84- having its focal point at85 on the same level with the free surface of the molten metal inbushing 59. This paraboloidal section merges at 86 over an arcuatesection 87 with the cylindrical inner wall section of mold 24.

As shown, the fixed crucible 14, fed with metal from the melting furnacethrough the shoot or runner 88 discharges through outlet 58 a verticaljet of molten metal 89 which drops down on to the bottom wall 60 of thebushing member 59 revolving at a high rate with the In this way acontinuous blank. This will Owing to the configuration of this section,the liquid jet tion into and through the annular space defined betweenthe inner wall of mold 24- and outer wall of bushing 59. There is inthis way created an annular sheet of molten metal continuously supplyingthe mold 24, thus promoting a smooth regular flow of metal and formationof the blank A.

The blank A formed by centrifugal action on the molten metal thussupplied in the embodiment of Figs. 3 and 4, solidifies owing to thecoolingeffect of the wall, as shown in Fig. 2, and is extracted from therotary mold in a continuous manner by suitable extracting means oneexemplary form of which is illustrated in Fig. 5. This figure shows onlyone (the right) half of the whole system in section, the other (leftside) half being symmetrical with respect to the right side half shownin detail.

The means for extracting the blank A comprise rollers 61, provided inany suitable number, and mounted with their axes forming equal,adjustable angles with respect to the axis of the system. Each roller 61is secured on a spindle 62 mounted in bearings 63, 64 in a cylindricalrollers 61 is then cut into sections by any suitable means.

red-hot temperature. This fuses the metal at the point of impact of theoxygen jet and provides a clear cut at the desired point of the blank.

In the construction shown in Fig. 6, a flange 75 is extending parallelto and spaced the mold, the flange supporting an annular pipe 77prooutlets or nozzles 78 supplied for example with acetylene and oxygenthrough the flexible hose connections 79, 80. Also attached to flange 75is a jet-nozzle 81 supplied with oxygen the jet from which is effectiveto sever the metal preliminarily heated by means of the burners 78.

The assembly comprising flange 75, and arcuate pipe 77 and nozzle 81attached thereto is slidable on guides 76 in order to be enabled tofollow the feed displacement of the blank during the heating and cuttingoperations. The displacement of the assembly along the guides 76 issynchronized with the displacement of the blank A through any suitableautomatic means, readily devisable by those familiar with the art, asfor instance by providing the flange 75 with sliding arms adjustable inlength and provided with retractable lugs cooperating with abuttingstops. The spacing between the stops and the arcuate heating pipe 77will vary according to the length of the desired pipe sections intowhich the blank is to be cut.

The flange 75 with its associated attachments is preferably balanced bymeans of a counterweight acting to urge it to its initial (uppermost)position after the cutting operation has been completed and the severedpipe section has been discharged.

The details of the embodiments described and illustrated are in no wayrestrictive and may be widely modified Within the scope of the claims.While the invention has been more particularly described as applied tothe continuous production of tubular blanks, this term should beunderstood in its broadest sense as designating any recessed metallicbody, whether tubular or otherwise.

In the drawings the set-up illustrated is one in which the blank isdisposed vertically. However, such a disposition is not restrictive, andthe invention may equally as well be embodied in arrangements whereinthe blank is arranged horizontally or at any angle to the horizontalplane.

What I claim is:

1. Apparatus for continuously producing metal tubular objects whichcomprises a container for receiving molten metal therein and having anoutlet, a mold comprising a removable open-ended cylindrical shell, anannular groove formed internally of said shell adjacent the upper endthereof and adapted to receive molten metal from said outlet, an annularflange on said shell at the upper end thereof and an annular guidesurface near the lower end of said shell, a cylindrical elementsurrounding the upper end of the shell and adapted to receive saidflange thereon, a further cylindrical element surrounding the lower endof the shell and having aperture means therein for guidingly engagingsaid guide surface of the shell, means for rotating both said elementsat a common speed, means for discharging a cooling fluid on the outermold wall between said mold and said upper element, means fordischarging the spent cooling fluid, means for extracting a solidifiedtubular object from the mold, means for adjusting said extracting meansin transverse dimension in accordance with the diameter of a tubularobject and means for controlling the longitudinal rate of extraction ofsaid object by said extracting means.

2. Apparatus for the continuous production of metal tubular objects,comprising means for receiving molten metal and having a molten metaloutlet, mold means comprising a removable open-ended cylindrical shell,an annular groove formed internally of said shell adjacent the upper endthereof adapted to be fed from said outlet, an annular flange adjacentthe upper end, an annular guide surface adjacent the lower end of saidshell, a cylindrical element surrounding the upper end of the shell andadapted to receive said flange thereon, a further cylindrical elementsurrounding the lower end of the shell and having aperture means forguidingly engaging said guide surface, means for rotating both elementsat a common rate, a plurality of separate spaced cooling fluid dischargemeans in the interval between said mold and said upper element fordischarging cooling fluid against the outer mold wall, individuallyadjustable means for separately supplying cooling fluid to saiddischarge means, means for evacuating the spent cooling fluid, rollersadapted to engage the solidified tubular object within the mold forextracting the object from the mold, said rollers mounted on axesangularly disposed with respect to the mold axis, rotatable and slidablecages supporting said rollers, and means for rotating said axes at anadjustable rate.

3. Apparatus for continuously producing metallic tubular objects,comprising means for receiving molten metal, mold means comprising aremovable open-ended cylindrical shell, an annular groove 'formedinternally of said shell adjacent the upper end thereof adapted to besupplied with metal from said outlet, a flange at the upper end, anannular projecting guide surface at the lower end of the mold, acylindrical element surrounding the upper end of the shell and having aportion adapted to receive said flange thereon, a further cylindricalelement surrounding the lower end of the shell and having an aperturefor guidingly engaging said annular surface, means for rotating saidelements at a common rate, a plurality of separate spaced cooling fluiddischarge means in the gap between said mold and said upper element fordischarging cooling fluid onto the outer mold wall, individuallyadjustable fluid supply means for each of said discharge means, meansfor leading off the spent cooling fluid, rollers circumferentiallyengaging said tubular object within the mold for extracting the objectfrom the mold, said rollers mounted on axes angularly disposed withrespect to the mold axis, rotatable and slidable cages supporting saidrollers, means for rotating said axes at an adjustable rate, and meansfor cutting off predetermined lengths of the solidified tubular objectand comprising a support having a heating range thereon and anoxygendischarge nozzle adjustable in position along said tubular object.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Serial No. 162,538, Roth (A. P. C.), published April 27,1943.

1. APPARATUS FOR CONTINUOUSLY PRODUCING METAL TUBULAR OBJECTS WHICHCOMPRISES A CONTAINER FOR RECEIVING MOLTEN METAL THEREIN AND HAVING ANOUTLET, A MOLD COMPRISING A REMOVABLE OPEN-ENDED CYLINDRICAL SHELL, ANANNULAR GROOVE FORMED INTERNALLY OF SAID SHEEL ADJACENT THE UPPER ENDTHEREOF AND ADAPTED TO RECEIVE MOLTEN METAL FROM SAID OUTLET, ANDANNULAR FLANGE ON SAID SHELL AT THE UPPER END THEREOF AND AN ANNULARGUIDE SURFACE NEAR THE LOWER END OF SAID SHELL, A CYLINDRICAL ELEMENTSURROUNDING THE UPPER END OF THE SHELL AND ADAPTED TO RECEIVE SAIDFLANGE THEREON, A FURTHER CYLINDRICAL ELEMENT SURROUNDING THE LOWER ENDOF THE SHELL AND HAVING APERTURE MEANS THEREIN FOR GUIDINGLY ENGAGINGSAID GUIDE SURFACE OF THE SHELL, MEANS FOR ROTATING BOTH SAID ELEMENTSAT A COMMON SPEED, MEANS FOR DISCHARGING A COOLING FLUID ON THE OUTERMOLD WALL BETWEEN SAID MOLD AND SAID UPPER ELEMENT, MEANS FORDISCHARGING THE SPENT COOLING FLUID, MEANS FOR EXTRACTING A SOLIDIFIEDTUBULAR OBJECT FROM THE MOLD, MEANS FOR ADJUSTING SAID EXTRACTING MEANSIN TRANSVERSE DIMENSION IN ACCORDANCE WITH THE DIAMETER OF A TUBULAROBJECT AND MEANS FOR CONTROLLING THE LONGITUDINAL RATE OF EXTRACTION OFSAID OBJECT BY SAID EXTRACTING MEANS.